I have a cedar home that is finished with Sikken's Cetol 1 & 23 plus. It's in need of restaining and my wife insist that we need to sand the exterior walls down to the bare wood. I think that compromises the protection of multiple coats and think we should only lightly sand where the finish is a bit bare, spot treat those bare areas with the base coat (Cetol 1) and then apply a maintenace coat to the entire wall with the 23 plus. Her concern is that the color will become darker than she would like with multiple coats. Any suggestions or am I doomed to sanding the entire wall?